The fourth debate of Republican candidates started badly for the front-runner Donald Trump. He was booed when he put down John Kasich with his oft-repeated line that the Ohio governor's turnaround of his state's economy was due to a windfall from fracking. That only gave Kasich an opening to give a granular enumeration of his achievements.

He had another bad moment when he went off on a rant against the Trans-Pacific Partnership and its supposed benefits for China, only to be corrected by Sen. Rand Paul, who pointed out that China had no part in the deal.

The real estate mogul tried to rally by answering a question about Syria, Ukraine and Russia with a boast that he could deal with President Vladimir Putin because they "were stablemates on '60 Minutes' and that went pretty well." This time, he was put in his place by Carly Fiorina: "I've met him as well, but it wasn't in a green room before a show. It was a private meeting."

Fiorina has become Trump's nemesis, putting him down at the second debate with the observation that everyone everywhere heard his remarks about her face.

In Milwaukee on Tuesday night, his irritation with her showed: After Fiorina tried to talk over Paul, Trump jumped in to ask, "Why does she keep interrupting everybody." That, too, elicited a hostile response from the crowd, which took her side against him.

Trump was all bombast, but in this debate it was those with substance who shined brightest -- Kasich, Marco Rubio, and Ted Cruz (though he had a Rick Perry-esque flub when he tried to list the government agencies he would kill off). Paul sounded informed even when he explained his case for a weak military.

And Trump's signature issue, immigration, did not serve him well. He gave his usual tough-guy speech on deporting all immigrants and forcing Mexico to pay for a wall. Kasich and former Gov. Jeb Bush both took him on, pointing out how ridiculous his proposal was. They got applause from a Republican audience. The act could be wearing thin.

The magnate's closing statement was all-Trump and no cattle. He was supposed to be telling people how he would fix the economy, but he engaged in more chest-thumping about the "tens of thousands of jobs," he's created with "the most iconic assets anywhere in the world," and promised to make America "even more special."

The repetition, the self-regard, the bragging have worked for him until now. But next to candidates who know something, he seemed shallow and unprepared. Go to a transcript and look for a sustained answer on policy. You won't find one.

Panicked Republicans were wondering what they could do to bring Trump down to earth. It turns out the debates, for all their failings, may do the trick.

Sure, the candidates embarrassed themselves by whining about the tone of the last one. They demanded less snark and more respect from Republican-friendly moderators. They got that, so much so that Fox Business News host Neil Cavuto said, "My goal is to make myself invisible."

Mission accomplished. Midway through the debate, five candidates spoke one after another without anyone stopping them.

The bell signaling time's up was ignored most of the time. Music played at one point to indicate a commercial break but even then the moderators were unable to cut in.

The net result was to allow the candidates to take each other on, giving viewers a few memorable moments that no moderator could have orchestrated.

We've been told that at some point, Republican voters would get past their anger and begin to look for a candidate who might be able to lead the country. That process finally may have begun Tuesday night.
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Margaret Carlson is a Bloomberg View columnist. A former White House correspondent for Time, she was also Time's first female columnist. She appeared on CNN's "Capital Gang" for 15 years. A former editor at the New Republic, Carlson has been a fellow at Harvard University's Institute of Politics, a Poynter Fellow at Yale University and a journalist-in-residence at the University of Notre Dame.